DE202020005654U1 - shell and tube heat exchanger - Google Patents

Abstract

Tube bundle heat exchanger (1) with an enveloping outer shell (2) and at least one tube sheet (3), which together define an interior space (4) of the tube bundle heat exchanger (1).
- a tube bundle with a large number of heat exchanger tubes (5), which are arranged in the interior (4) and through which a first heat transfer fluid can flow and are optionally supported by additional support plates (6), the heat exchanger tubes (5) having external ribbing (51) on their outside exhibit,
- At least one inlet (8) on the outer jacket (2) through which a second heat transfer fluid flowing around the heat exchanger tubes (5) can be introduced into the interior (4), and at least one outlet (9) through which the second heat transfer fluid can be discharged from the interior (4) can be derived,
- optionally at least one connection box (7) arranged on the at least one tube plate (3) for distribution, deflection or collection of the first heat transfer fluid, characterized in that
- that the heat exchanger tubes (5) enter the tube sheet (3) at passage points (31) with their outer ribbing (51) or pass through the tube sheet (3), and
- that at these passage points (31) the heat exchanger tubes (5) have a material connection (32) to the tube sheet (3).

Description

The invention relates to a tube bundle heat exchanger according to the preamble of claim 1.

Shell and tube heat exchangers are used to transfer heat from a first fluid to a second fluid. For this purpose, a shell-and-tube heat exchanger usually has a hollow cylinder inside which a large number of tubes are arranged. One of the two fluids can be passed through the tubes, the other fluid through the hollow cylinder, in particular around the tubes. The ends of the tubes are fastened to a tube sheet or several tube sheets of the tube bundle heat exchanger along their circumference. In the course of the manufacturing process of a tube bundle heat exchanger, the ends of the tubes are connected to the tube sheet, for example with a material fit.

The publication WO 2017/025 184 A1 describes a method for connecting tubes of a tube bundle heat exchanger to a tube sheet. The tubes and the tube sheet are each made of aluminum or an aluminum alloy and are bonded to the tube sheet by means of laser welding. The intensity of the generated laser beam is over 1 MW/cm2. It is also considered that the tubes of the tube bundle heat exchanger are positively connected to the tube sheet before the laser welding.

In its finished, ready-to-operate state, the tube bundle heat exchanger to be manufactured has a large number of tubes, which are arranged inside a hollow cylinder. The tube sheet can be designed as a plate and has bores whose diameter essentially corresponds to the outer diameter of the tubes. Each tube is fastened with one of its ends to one of these bores.

The tubes can run in a straight line within the hollow cylinder as a straight-tube heat exchanger. In this case, two tube sheets are provided, which are arranged at opposite ends of the straight-tube heat exchanger. Each tube is attached with one of its ends to one of these two tube sheets.

The tubes can also run in a U-shape within the hollow cylinder as a U-tube heat exchanger. Such a U-tube heat exchanger usually has only one tube plate. In this case, since the tubes are bent into a U-shape, they can be attached to the same tube plate at both ends

From the DE 10 2006 031 606 A1 a method for laser welding a heat exchanger for exhaust gas cooling is known, in which an oscillating movement is also superimposed on a feed movement of the laser beam. This pendulum movement takes place essentially in the direction perpendicular to the feed direction. The pendulum movement is carried out for reasons of better bridging of gaps

Furthermore, a method for connecting tubes of a tube bundle heat exchanger to a tube plate is known from publication WO 2017/125 253 A1. The tubes are firmly bonded to the tube sheet by means of laser welding. For the connection, a laser beam is generated and focused on a point to be welded in a connection area between tube and tube sheet. Here, the laser beam is moved in such a way that it completes a first movement across the connection area and a second movement that is superimposed on the first movement and that is different from the first movement. The second movement specifically influences the melt pool dynamics and advantageously modifies a vapor capillary that is created.

The object of the invention is to connect tubes of a tube bundle heat exchanger to a tube plate reliably and with little effort and with high quality

The invention is represented by the features of claim 1. The further dependent claims relate to advantageous developments and refinements of the invention.

The invention includes a tube bundle heat exchanger with an enclosing outer shell and at least one tube sheet, which together define an interior space of the tube bundle heat exchanger. The tube bundle heat exchanger comprises a tube bundle with a plurality of heat exchanger tubes arranged in the interior through which a first heat transfer fluid can flow and are optionally supported by additional support plates, the heat exchanger tubes having external ribbing on their outside. The tube bundle heat exchanger comprises at least one inlet on the outer shell, through which a second heat exchanger fluid flowing around the heat exchanger tubes can be introduced into the interior, and at least one outlet through which the second heat exchanger fluid from the Interior can be derived. The tube bundle heat exchanger optionally includes at least one connection box arranged on the at least one tube plate for distribution, deflection or collection of the first heat transfer fluid. At passage points, the heat exchanger tubes enter the tube sheet with their outer ribbing or through the tube sheet. At these passage points, the heat exchanger tubes have an integral connection with the tube sheet. As a result, the outer ribbing is also directly adjacent to the tube sheet wall or comes into contact with it.

In other words: the heat exchanger tubes have external ribbing within the passage points at which they pass into a tube sheet or through a tube sheet. This outer ribbing is surrounded by the material for a material connection and the passage of gas or liquid is thus hermetically sealed. For a pure material connection, combinations together with a force fit and a form fit can also be used in an advantageous manner.

For external ribbing, a heat exchanger tube can also optionally have an internal structure. The internal structure can be designed in the form of an internally circumferential helix with a predetermined helix angle. In the event that the outside of the heat exchanger tubes has spiral outer ribbing, the pitch of the encircling outer ribbing can be the same as, less than or greater than the pitch of the encircling helix predetermined by the twist angle. The two structures can consequently differ in that for the integral connection of the outside of a heat exchanger tube to the container wall, the design of the external ribbing and the internal structure can be designed independently of one another and can thus be optimized.

To optimize the heat exchange, however, both structures are subject to certain limits. The ratio of the maximum structure height of the outer ribbing and the maximum structure height of the inner structure is preferably in the range from 1.25 to 5 for condenser tubes and preferably in the range from 0.5 to 2 for evaporator tubes.

Above all, investment costs are to be saved, since the tube bundle heat exchanger according to the invention can be built much more compactly. The outer ribbing extends to the tube sheet, which means that the number of heat exchanger tubes per unit can be significantly reduced. Depending on the requirements, the finned tubes enable more efficient use of energy or the reduction of filling quantities, which lowers operating costs.

The invention is based on the consideration that an integral connection of the heat exchanger tubes to the tube sheets is achieved in a particularly reliable and low-cost manner with high quality. According to the invention, a heat exchanger tube with its external ribbing on the outside enters the tube sheet or passes through the tube sheet. The outer ribbing then remains immediately adjacent to the material connection of the tubes with the tube sheet. This has the particular advantage that inside the tube bundle heat exchanger, the heat exchanger tubes have continuous external ribbing for efficient heat transfer.

Advantageously, the material connection can be gas-tight and pressure-resistant. In addition to the mechanical stability features associated with efficient heat transfer, hermetic sealing to prevent fluid exchange with the environment is important in any mode of operation.

In an advantageous embodiment of the invention, the heat exchanger tubes in the points of passage have an inside diameter D2 that is larger than the inside diameter D1 of the heat exchanger tubes outside of the points of passage.

If the heat exchanger tubes still have external ribbing within the passage points at which they enter or pass through the tube sheet, the process is based on a widening of the heat exchanger tube with the result of an enlarged inner passage diameter D2. The outer ribbing is then squeezed within a penetration point by a widening. Nevertheless, the material connection ultimately ensures a stable hermetic seal.

In an advantageous embodiment of the invention, the heat exchanger tubes can be soldered, glued or welded into a tube sheet. In addition to the preferred types of connection mentioned, others can also be added which reliably join the heat exchanger tubes to the tube sheet by means of a materially bonded connection.

In principle, the outer ribbing on the outside of the heat exchanger tubes can preferably run in the circumferential direction or in the axial direction parallel to the tube axis. In an advantageous embodiment of the invention, the outside of the heat exchanger tubes can have a spiral lig circumferential outer ribbing. In the case of spiral external ribbing, only a residual gap and the channel that runs around spirally with external ribbing must be reliably sealed by the material connection.

Even if a suitable uniform material is generally preferred for the heat exchanger tubes, in an advantageous embodiment of the invention at least one first heat exchanger tube can consist of a first material and at least one second heat exchanger tube can consist of a second material which differs from the first material. With regard to mechanical stability, steel pipes with particularly high strength can offer a particular advantage. Copper tubes, on the other hand, result in optimization with regard to efficient heat transfer. Other materials such as titanium, aluminum, aluminum alloys and copper-nickel alloys can also be considered.

Exemplary embodiments of the invention are explained in more detail with reference to the schematic drawings.

• 1 schematisch eine Seitenansicht eines Rohrbündelwärmetauschers,
• 2 schematisch eine Frontansicht eines Ausschnitts eines Rohrbodens mit Durchtrittsstelle, und
• 3 schematisch einen senkrechten Schnitt des Rohrbodens in der Ebene der Durchtrittsstelle der Wärmeaustauscherrohre.

Show in it:

• 1 schematically a side view of a tube bundle heat exchanger,
• 2 schematically shows a front view of a section of a tube sheet with passage point, and
• 3 schematically a vertical section of the tube sheet in the plane of the point of passage of the heat exchanger tubes.

Corresponding parts are provided with the same reference symbols in all figures.

1 shows a schematic side view of a tube bundle heat exchanger 1 with an enveloping outer shell 2 and two tube sheets 3 which together define an interior space 4 of the tube bundle heat exchanger 1 . The tube bundle heat exchanger 1 comprises a tube bundle with a multiplicity of heat exchanger tubes 5, which are arranged in the interior 4 and through which a first heat transfer fluid can flow and are supported by additional support plates 6. Such support plates 6 are also often used as guide plates for the flow of fluid. The tube bundle heat exchanger 1 also includes connection boxes 7, which distribute, divert or collect the first heat transfer fluid inside the heat exchanger tubes, depending on requirements. There is at least one inlet 8 on the outer jacket 2, via which a second heat transfer fluid can be introduced into the interior, and at least one outlet 9 via which the second heat transfer fluid can be discharged from the interior.

2 shows a schematic front view of a section of a tube sheet 3 with passage points 31. At a passage point 31, the recess in the tube sheet wall 33 is preferably just large enough for a heat exchanger tube 5 to be inserted with its outer ribbing 51 and bonded there. Adhesive and soldered connections as a material connection 32 can be made at the passage point 31 over the entire wall thickness of a tube sheet 3 . Welded connections as an integral connection 32 can be arranged on the outside and/or inside on the tube sheet 3 . If the melt flow is favorable, a weld connection through the entire wall thickness can be established at the passage point 31 even with one-sided welding from the outside or inside of the tube sheet wall 33 of a tube sheet 3 .

3 FIG. 1 schematically shows a vertical section of the tube sheet 3 along the section line AA 2 in the plane of the point of passage 31 of a heat exchanger tube 5. The heat exchanger tube 5 shown has external ribbing 51 on the outside. The heat exchanger tube 5 passes through the tube sheet wall 33 at the passage point 31 . At this passage point 31 , the heat exchanger tube 5 has continuous outer ribbing 51 and a material connection 32 in the form of a continuous weld seam with the tube sheet 3 . Depending on the combination of materials from the tube plate 3 and from the heat exchanger tube 5, advantageous new intermetallic phases can form in the melt bath at the weld point 32. Laser welding in particular is a suitable method for producing a material connection with a locally limited melt flow.

Reference List

1

shell and tube heat exchanger

2

outer jacket

3

tube sheet

31

passage points

32

material connection

33

tube sheet wall

4

inner space

5

heat exchanger tube

51

external ribbing

6

gusset

7

junction box

8th

inlet

9

outlet

D1, D2

pipe inside diameter

arrow

fluid flow

A-A

cutting line

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102006031606 A1 [0007]

Claims (5)

Tube bundle heat exchanger (1) with an enveloping outer jacket (2) and at least one tube sheet (3), which together define an interior (4) of the tube bundle heat exchanger (1), comprising - a tube bundle with a multiplicity of heat exchanger tubes (5) which are in the interior ( 4) are arranged through which a first heat transfer fluid can flow and are optionally supported by additional support plates (6), the heat exchanger tubes (5) having external ribbing (51) on their outside, - at least one inlet (8) on the outer jacket (2), via through which a second heat transfer fluid flowing around the heat exchanger tubes (5) can be introduced into the interior (4), and at least one outlet (9) via which the second heat transfer fluid can be discharged from the interior (4), - optionally at least one on the at least a tube sheet (3) arranged junction box (7) for distribution, deflection or collection of the first heat transfer fluid, characterized in that net , - that the heat exchanger tubes (5) enter the tube sheet (3) with their outer ribbing (51) at passage points (31) or pass through the tube sheet (3), and - that at these passage points (31) the heat exchanger tubes (5) have a material connection (32) to the tube sheet (3). Tube bundle heat exchanger (1) according to claim 1 , characterized in that the material connection (32) is gas-tight and pressure-resistant. Tube bundle heat exchanger (1) according to claim 1 or 2 , characterized in that the heat exchanger tubes (5) in the passage points (31) have a tube inner diameter D2 which is larger than the tube inner diameter D1 of the heat exchanger tubes (5) outside the passage points (31) Shell and tube heat exchanger (1) according to one of Claims 1 until 3 , characterized in that the heat exchanger tubes (5) are soldered, glued or welded into a tube plate (3). Shell and tube heat exchanger (1) according to one of Claims 1 until 4 , characterized in that the outside of the heat exchanger tubes (5) has external ribbing (51) running around in a spiral.

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